These days, in a semiconductor process, as a means for evaluating whether or not a formed pattern is as designed, the shape of the pattern is managed with dimensions by measuring the width of a line pattern or the size of the diameter of a hole by using a critical dimension-scanning electron microscope (CD-SEM), and in recent years, strict dimension control is necessary along with the miniaturization of semiconductors.
In a projection exposure method of transferring a semiconductor circuit pattern onto a wafer, exposure light is applied to the photomask of a shielding material in which the circuit pattern to be printed is written and the image of the photomask is projected onto a resist on the wafer through a lens system to create a circuit pattern. One chip or a plurality of chips are printed with one exposure shot, and a circuit pattern is formed on the wafer with a plurality of exposure shots.
When exposing with an exposure device, exposure is performed by appropriately determine a focus and an exposure amount, which is an exposure condition. However, even if exposure is performed by uniformly determining the focus and the exposure amount to appropriate values, there is a problem that a normal circuit pattern is not created or the variation in dimensions of the pattern becomes large because the values of the focus and the exposure amount deviate from the appropriate values by roughness on the surface of the resist due to uneven resist coating, non-flatness due to the photomask, aberration of the lens, and the like.
The deviation of the exposure condition caused by resist coating, photomask, and lens aberration is reproducible. A method of measuring the shape of a circuit pattern on a Focus Exposure Matrix (FEM) wafer created in advance under a plurality of exposure conditions by changing the exposure condition with the semiconductor measurement device and evaluating a relationship between the exposure condition and the circuit pattern shape to estimate the exposure condition from the circuit pattern shape measured by a semiconductor measurement device is known (see PTL 1). By feeding back exposure parameters estimated by this method to an exposure machine, it is possible to perform exposure in which the deviation of the exposure condition is corrected.